Nail carrying structures

ABSTRACT

An article of manufacture is provided which enables nails to be fed serial fashion to a nail-driver device. The article of manufacture comprises a strip shaped to provide a series of apertured nail flanges connected to each other by a mechanically weakened linkage, and nails disposed in the apertures of the flanges.

RELATED APPLICATION

This application is a division of my copending U.S. Pat. applicationSer. No. 312,665 for Improvements in Fastener-Driving Apparatus andProcesses, filed Dec. 6, 1972, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 68,423 forImpact Tools, filed Aug. 31, 1970 by Clifford and Haytayan. Said U.S.patent application Ser. No. 68,423 issued as U.S. Pat. No. 3,711,008 onJan. 16, 1973.

BACKGROUND OF THE INVENTION

Pneumatic nail-driving tools are old in the art. They are characterizedby loud operation, by substantial recoil, and a limited performancecharacteristic. Among such devices disclosed in the existing art arethose disclosed in U.S. Pat. Nos. 3,498,517 to Novak; 3,060,441 toHenning; 3,035,268 to Goldring; 3,060,440 to Pfaff; 3,595,460 to Pitkin.Another such device is disclosed in U.S. Pat. No. 3,711,008

As a consequence of the limited capability of pneumatic driving devicesknown to the art most heavy-duty fastener-driving operations are carriedout with explosive-actuated devices which are not only time-consumingand expensive to operate, but also which, because of the danger inherentin such devices, require licensed operators. Moreover recoil and noiseproblems associated with the pneumatic devices are inherent--and usuallymore pronounced--in the explosive-actuated fastener driving means. Theprior art, therefore, has nowhere provided a pneumatic nail drivingmachine which is useful in heavy-duty, fastener-driving applications,e.g., those applications requiring an input of about 1,250 inch-lbs ormore of work to drive the nail into the substrate. And even thosepneumatic machines available for relatively light-duty fastening taskshave been excessively noisy, and have had an annoying recoil.

In addition to these problems associated with fastener driving means theart has encountered a further problem relating to the feeding of flangednails into the driving devices. Flanged-head nail configurations areoften required by building code and have heretofore been fed one-by-oneinto the driving means. These nails generally include a sliding flangewhich aids in maintaining perpendicularity of the nail which, inaddition to being an impact-receiving member, provides a seat for thesliding flange. It is this sliding flange, on being displaced during thenailing stroke, which forms the main portion of the head of a drivennail. Thus, it was desirable to provide improved means for feeding nailsto a pneumatic nailing machine.

SUMMARY OF THE INVENTION

It is an object of the invention to provide improved apparatus fordriving fasteners, e.g. nails, through wood or even steel strips, intohighly resistant structural masses such as those formed of concrete.

Another object of the invention is to provide such an apparatus which isconvenient to operate and has relatively low noise and relatively littlerecoil when compared to prior art devices capable of performingequivalent or similar fastening tasks.

Another object of the invention is to provide a new and highly efficientpneumatic actuating apparatus.

Still another object of the invention is to provide a novel process fordriving fasteners by pneumatic actuating means.

Another object of the invention is to provide improved processes forfastening flanged nails with pneumatic nailers.

A further object of the invention is to provide novel process for makinga novel fastener assembly particularly well adapted for use in automaticfeeding of fasteners into a fastening device.

Another object of the invention is to provide a novel relief valveconstruction which is particularly useful in the fastening devices ofthe invention.

Other objects of the invention will be obvious to those skilled in theart on reading the instant application.

The above objects have been accomplished by construction of apneumatically actuated fastener-driving tool which is characterized by astructure wherein:

1. the driving member or hammer is substantially free of mechanicalimpedance during an acceleration stroke and is returned to its originalposition by pneumatic means; for example, it is not required to transferenergy to a spring or other such device on its work stroke;

2. vent means is provided for exhausting air from between the pneumaticpiston and the work piece during the impact stroke of the nail head;

3. the hammer is caused to accelerate over a substantial path before itstrikes the work with the fastener, i.e. a path at least about as longas the nail height or longer;

4. an air supply sized and valved to substantially increase theacceleration of the hammer throughout a major portion of its downwardstroke;

5. a quick-acting, wide-mouthed valve means is utilized to assure rapidsupply of motivating air to the piston during the hammer stroke.

In practice, it is desirable to operate the apparatus of the inventionso that the energy delivered to the nail head is at least about 30percent greater than the energy required to achieve the intendedfastening action. For example, if the required work is 1,500 inch-lbs,the pneumatic hammer should be of such size and weight that at leastabout 2,000 inch-lbs of work is deliverable at the nail head. This extraenergy has been found of particular value in limiting recoil effects.

Although the inventor does not wish to be bound by the following theory,one established after a comparative study of his apparatus and thoseknown to the prior art, it is his opinion that the particular attributesof his invention relate to the higher initial impact force which theinstantly-disclosed apparatus can achieve and to the means by which thisimpact force is generated. Most prior art devices used in pneumaticdriving of nails have been static devices; by static devices is meantdevices that provide for little or no acceleration time between theactuation of the hammer part and the impacting of the work by thefastener to be driven by the hammer part.

The inventor avoided this problem, during work initially intended todevelop a small-diameter device, by providing a dynamic device whereinhis hammer member travels for distance of at least the height of thenail to be driven before impact. However, the approach alone did notsolve his problem. In part this appeared to be because spring biasdevices used to return the hammer to its starting position providedsufficient energy absorption and mechanical impedance to the forwardstroke of the hammer. With the removal of such mechanical impedancedevices, it became necessary to provide alternate return means and, inthe course of such work, applicant discovered that it was also desirableto provide gas-escape means below the pneumatic piston. Finally,applicant discovered that when the hammer was provided with a relativelyobstruction-free air supply system to take full advantage of theacceleration capability made possible by the removal of the spring andthe addition of the vent means, he could achieve results not achievablewith any pre-existing pneumatic fastener-driving tool. He furtherdiscovered that use of a quick-acting, widemouthed valve allowed a highrate of acceleration of the hammer to start immediately.

To provide an improved nail feed means to complement the capabilities ofhis new driving tool, applicant has constructed a continuous metallicstrip formed of flanges into which nails are snugly fitted. The flangesare connected at relatively weak sections of the strip and break offindividually when the high initial force is transmitted thereto by theaction of the hammer on the nail head. A convenient means for formingthis nail-bearing strip is to stamp a strip of metal with a series ofspaced holes for receiving nails, and to have the desired shape of aseries of flanges. A plurality of strips may be used but one isgenerally sufficient to provide an adequate serial feed to theapparatus.

ILLUSTRATIVE EMBODIMENT OF THE INVENTION

In this application and accompanying drawings there is shown anddescribed a preferred embodiment of the invention and suggested variousalternatives and modifications thereof, but it is to be understood thatthese are not intended to be exhaustive and that other changes andmodifications can be made within the scope of the invention. Thesesuggestions are selected and included for purposes of illustration inorder that others skilled in the art will more fully understand theinvention and the principles thereof and will be able to modify it in avariety of forms, each as may be best suited in the condition of aparticular case.

IN THE DRAWINGS

FIG. 1 is a section, partially diagrammatic, showing a nail driveraccording to the invention with the hammer in a retracted or readyposition.

FIG. 2 is a more detailed section of the quick-opening, wide-mouthedvalve structure sealing the top of a pneumatic cylinder seen in FIG. 1.

FIG. 3 is a more detailed view of a check valve useful with theapparatus of the invention.

FIG. 4 is a section, partially diagrammatic, showing a nail driveraccording to the invention with the hammer at the completion of itsnail-driving stroke.

FIGS. 5, 8 and 11 show elevations of various nail-holding strips usefulin feeding the apparatus of the invention.

FIGS. 6, 9 and 12 are plan views of the strips shown in FIGS. 5, 8 and11, respectively.

FIGS. 7, 10 and 13 are elevations showing nails properly mounted in thestrips of FIGS. 5, 8 and 11, respectively.

Referring to FIG. 1, it is seen that a nail-driving tool 12 comprises apneumatic cylinder housing portion 14, a nail-receiving and positioningsection 16, and a pneumatic control assembly 18.

Housing 14 comprises a cap member 20, at the top thereof, a valvehousing 21 mounted just below cap member 20, and a fastener-positioningassembly 22 at the bottom of cylinder 14 in addition to the main housingcylinder tube 24. Tube 24 encloses an interior tube 26. Tube 26 is acylinder forming a primary pneumatic chamber 28 in which piston means 30is adapted to reciprocate in response to various pressure differentialsto be described below. An annular chamber 32 between tubes 24 and 26serves as the primary pressurized air supply path connecting the upperportion of chamber 28, i.e. chamber 28a, with pneumatic control section18 and a pressurized air supply port 86. Chamber 32 has a volume that isabout two times, but more advantageously four times, the volume ofchamber 28a when the hammer is in the position shown in FIG. 4.

A secondary air path is formed by a conduit 34 mounted in chamber 32 andconnecting the pneumatic control section 18 with pneumatic chamber 106through cap member 20.

Lower piston face 31, when in the retracted position of FIG. 1, isattached to the top of hammer member 42 and is pneumatically sealed tothe inner wall 44 of tube 26 by seal means 48 in a manner similar tothat in which seal means 46 seals piston face 37 to the inside ofchamber 28b. Seated on top of tube 26 is a top valve element 50 formingthe bottommost face 29 of air valve 51. Valve 51 comprises a centrallylocated vent 52 which extends from the bottom face 29 of valve element50. Valve 51 is positioned and sealed in cap member 20 and valve housing21 by means of O-ring type seals 55, 56, and 57. It will be noted (seeFIG. 2) that valve member 50 comprises an annular portion 49 of face 29upon which gas in chamber 32 can exert upward pressure. It is thispressure that will thrust the valve open when pressure is released fromspace 106 between valve 51 and cap 20. It will be further noted thatseveral small air ports 53 spaced around and through tube 26 providemeans to admit air from annular chamber 32 into that portion of chamber28, i.e. chamber 28b, which is sealed between the upper and lower pistonfaces of piston member 30. In this connection, it will be noted that thelower piston face 35 of chamber 28b is smaller than the upper pistonface 37. The resultant force differential tends to keep piston member 30permanently biased toward a normal upward position.

It will be noted that below piston face 31 and just proximate the bottomof chamber 28, a series of conduits 60 provide means to vent the lowerportion of chamber 28 to atmosphere. Conduits 60 are partially formed ina lower cylinder plug member 62.

Fastener positioning assembly 22 comprises a guide path 64 for hammer42. This path 64 is through a positioning foot 66 which assures theperpendicularity of fasteners 68 with the substrate, here wood 70 andconcrete 72, into which the fasteners are to be driven. A plurality offasteners 68 of preselected height are conveniently fed into the path ofhammer 42 from a pre-assembled cartridge 78.

Pneumatic control assembly 18 comprises a three-way pneumatic valve 80,a valve-actuating trigger 82 pivotally mounted on an adaptor member 83which is, in turn, mounted on cylinder 14, and an air inlet manifold 84comprising port 86 leading from an air supply source, port 88 leading tovalve 80, port 90 leading to annular chamber 32. As best seen in FIG. 3,housing 87 of valve 80 holds a ball-shaped valving member 92 which canbe seated against either seat 94 or seat 96, depending on the positioninto which operating rod 98 is positioned by trigger 82. When the ball92 is in sealing contact with seat 94, there is an open air path betweenconduit 34 and vent 100 to atmosphere. When ball 92 is seated againstseat 96, conduit 34 and the main air supply are in contact through valveconduit 102.

Operation of the Nail-Driving Unit

In general, it will be noted that FIGS. 1 through 3 show the apparatusof the invention before it is triggered to drive a nail. FIG. 4illustrates the apparatus just as the driving stroke is terminated. Withthe apparatus in the position shown in FIGS. 1 through 3 the operatorplaces the device over the desired location and pulls trigger 82.

It will also be assumed for purposes of this description that, beforethe trigger is pulled, a compressed air source is connected to port 86and with the apparatus in the ready position causes a 125-psig pressurein the chamber of gas inlet manifold 84; in annular chamber 32, inconduit 34, in the space 106 between the top face 51s of top air valve51, and in that chamber 28b which is sealed between piston surfaces 37and 35, i.e. between seals 46 and 48. Air flows into 28b through holes53 from annular chamber 32.

There is no pressure on the upper face 30a of piston member 30 becauseface 30a is directly in contact with the atmosphere through vent 52. Inthis condition, therefore, the piston member 30 is held upwardly by theaforesaid pressure differential.

When the operator wishes to drive the nail into the wood-and-concretesubstrate, he pulls trigger 82 upwardly; this causes ball element 92 toleave seat 96 and to be seated against seat 94.

The following changes, all indicated in FIG. 4, take place immediately:

1. Air rushes down conduit 34 and back to atmosphere through valve 80and vent 100. This removes any force from holding valve 51 in itsdownward, or venting, position. Valve 51 raises immediately sealingvents 52 against a vent-valve seat 110.

2. Simultaneously, of course, a generally cylindrical inlet 112 isformed around the periphery of inner tube 26. Air pours through thisopening onto the top face 30a of piston 30.

3. Piston 30 immediately starts downwardly. Air pushed downwardly beforepiston member 30 vents to atmosphere through conduits 60.

4. Piston 30 accelerates hammer 42 through guide path 64 and,consequently, causes the hammer to drive a nail into the wood-concretesubstrate as shown in FIG. 4.

When member 92 of valve 80 is reseated into the position of FIGS. 1through 3, either automatically or by manual action, the flow of airagain reverses through conduit 34 and pressure is again brought againstsurface 51s of valve 51, tending to force it downward to once again openthe vent system associated with conduit 52. Air is then expelled upwardfrom chamber 28 through vent 52. Simultaneously air enters holes 53below piston face 37 and pushes the piston with its attached hammermember upwardly, this occurring because of the aforementioned areadifferential between surfaces 37 and 35.

It should be emphasized that the peculiar advantages of the inventionare related to (1) providing a suitable acceleration time for the hammerbefore it impacts the fastener; and (2) making certain that theaccelerating time is well-utilized. The first item is taken care of byproviding a suitable distance between the point at which the hammer isfirst set in motion and the point that it hits the fastener. However, anumber of features are required, or at least highly advantageous inassuring an optimum rate of acceleration during the impact stroke.

The first of these features is the maintenance of a suitable gas supplyto the piston. Unless an excellent supply of motive gas is maintained,the piston, after initial acceleration, can tend to be starved and failto meet its optimum potential. In structural terms, it is desirable thatthe motive gas be supplied from chamber 32 to the piston through a valveopening which is not too small. This opening should be, at pressurebelow 200psig, such that the ratio of the area of the operating surfaceof the piston itself to the valve opening itself is no greater than 8 to1 (or the pneumatic equivalent thereof) when there are no other seriousflow obstructions in the path of the motivating gas. The best practiceis to keep this ratio below 4 to 1 when operating at pressures below 130psi. Of course, even this feature of the invention will not beefficacious if the pressure-gas storage area is unduly limited, and theair supply to the storage volume is unduly constricted.

In the illustrated embodiment of the invention, this feature isillustrated by use of a slot 200. This is about 3/4 inch by 5/16 of aninch and are suitable for use with a 2 inch diameter piston and 125 psigwhen chamber 32 is about 2.3 times the volume of 28a when 28a isexpanded as seen in FIG. 4.

A particular feature of the invention is the rapid-opening valveallowing a fast and large supply of compressed air into the pistonchamber. This valve opens wide within about 1.7 milliseconds inapparatus wherein the piston itself has a hammer-actuating stroke of 7milliseconds. This is in the case of a typical five-inch stroke. Thusthe advantageous process of the invention is one wherein the valve fullyopens within the first 25 percent of the total time required to drivethe piston through its hammer-actuating stroke.

As has been mentioned above, it is also desirable to remove suchacceleration-impeding devices as return springs, to provide a pneumaticreturn means, and to provide vent means below the piston. However, atsufficient pressures, those skilled in the art will realize such devicesmay be tolerated.

It will be noted that the nail receiving and positioning section 16 isadapted to comprise a cartridge 78 from which nails 68 are fed underhammer stroke path 64. In prior practice, the flanged-head nails of theillustration have not been convenient for use with such apparatus. FIGS.5 through 7 show a means for connecting the nails 130 by punchingapertures 132 in a steel strip 134, punching away the outer periphery ofthe strip to form a series of circular flanges 136, and forming weakenedconnector points 138 between the flanges. Nails 130 are convenientlyfitted snugly within apertures 132. A recessed bearing surface 140 maybe formed into the strip about the uppermost part of aperture 132 toallow the nail to be driven flush with the flange.

It should be understood that when the nails are fed thusly into thefastener device of the invention, the nail will be driven downwardlythrough the flange and be separated from strip 136 at points 138.

FIGS. 8-10 disclose a nail-carrying structure similar to that shown inFIGS. 5-7 excepting that there is no nailhead-receiving recess in themetal strip and the flanges are already on the nail's striking surface.

FIGS. 11-13 disclose a nail-carrying structure similar to that shown inFIGS. 5-7 excepting that the nails are so-called T-nails rather than theordinary flanged-head nails.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which mightbe said to fall therebetween.

I claim:
 1. An article of manufacture comprising a shaped strip havingthe general exterior outline of a number of circular nail flangesconnected in series, apertures in said strip adapted to hold nailssnugly therein, a mechanically weakened linkage at the point ofconnection between each pair of adjacent flanges, and a T-nail in eachaperture, each flange having a diametrically-extending recess on oneside to receive the head of a T-nail so that said head can be disposedflush with said flange.
 2. An article of manufacture as defined in claim1 wherein said strip is made of metal.
 3. An article of manufacturecomprising a shaped strip having the form of a row of circular nailflanges with (1) each pair of successive flanges having a point ofmutual tangency, (2) a mechanically weak linkage connecting each flangeto an adjacent flange at their point of mutual tangency, and (3) anaperture in each flange, and a nail disposed in each aperture with theopposite ends of said nails being spaced from said flanges, each nailhaving a head at one end with the maximum cross-sectional dimension ofsaid head being smaller than the diameter of the flange with it isassociated, said heads being spaced from one another.
 4. An article ofmanufacture as defined in claim 3 wherein said strip is made of metal.5. An article of manufacture according to claim 3 wherein each of saidflanges has a recess concentric with its aperture which is sized toaccomodate the head of the nail associated with said flange.
 6. Anarticle of manufacture according to claim 6 wherein each said head has asloping outer surface and each of said recesses is tapered according tothe slope of the said outer surfaces of said nail heads.